From e7e430af64ab924350af21cbd82a345f4bba5f61 Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Wed, 20 Mar 2024 05:02:40 +0100
Subject: [PATCH 01/19] Make Counter generic over the value

Closes: #3438
---
 stdlib/collections/__init__.pyi               |  7 +++--
 .../stdlib/collections/check_counter.py       | 31 +++++++++++++++++++
 2 files changed, 35 insertions(+), 3 deletions(-)
 create mode 100644 test_cases/stdlib/collections/check_counter.py

diff --git a/stdlib/collections/__init__.pyi b/stdlib/collections/__init__.pyi
index 1d23ecd66a8d..ccd0023a9190 100644
--- a/stdlib/collections/__init__.pyi
+++ b/stdlib/collections/__init__.pyi
@@ -34,6 +34,7 @@ _KT = TypeVar("_KT")
 _VT = TypeVar("_VT")
 _KT_co = TypeVar("_KT_co", covariant=True)
 _VT_co = TypeVar("_VT_co", covariant=True)
+_C = TypeVar("_C", default=int)
 
 # namedtuple is special-cased in the type checker; the initializer is ignored.
 def namedtuple(
@@ -261,13 +262,13 @@ class deque(MutableSequence[_T]):
     if sys.version_info >= (3, 9):
         def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
 
-class Counter(dict[_T, int], Generic[_T]):
+class Counter(dict[_T, _C]):
     @overload
     def __init__(self, iterable: None = None, /) -> None: ...
     @overload
-    def __init__(self: Counter[str], iterable: None = None, /, **kwargs: int) -> None: ...
+    def __init__(self: Counter[str, _C], iterable: None = None, /, **kwargs: _C) -> None: ...
     @overload
-    def __init__(self, mapping: SupportsKeysAndGetItem[_T, int], /) -> None: ...
+    def __init__(self: Counter[_T, _C], mapping: SupportsKeysAndGetItem[_T, _C], /) -> None: ...
     @overload
     def __init__(self, iterable: Iterable[_T], /) -> None: ...
     def copy(self) -> Self: ...
diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
new file mode 100644
index 000000000000..9b6f74b4736a
--- /dev/null
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -0,0 +1,31 @@
+from collections import Counter
+from typing_extensions import assert_type, Never
+
+
+class Foo: ...
+
+
+# Test the constructor
+assert_type(Counter(), Counter[Never, int])
+assert_type(Counter(foo=42.2), Counter[str, float])
+assert_type(Counter({42: "bar"}), Counter[int, str])
+assert_type(Counter([1, 2, 3]), Counter[int, int])
+
+int_c: Counter[str] = Counter()
+assert_type(int_c, Counter[str, int])
+int_c["a"] = 1
+int_c["a"] += 3
+int_c["a"] += 3.5  # type: ignore
+
+float_c = Counter(foo=42.2)
+assert_type(float_c, Counter[str, float])
+float_c["a"] = 1.0
+float_c["a"] += 3.0
+float_c["a"] += 42
+float_c["a"] += "42"  # type: ignore
+
+custom_c: Counter[str, Foo] = Counter()
+assert_type(custom_c, Counter[str, Foo])
+custom_c["a"] = Foo()
+custom_c["a"] += Foo()  # type: ignore
+custom_c["a"] += 42  # type: ignore

From fc7af5567714b5d07be26c2cf45bd99db9259da8 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Wed, 20 Mar 2024 04:05:19 +0000
Subject: [PATCH 02/19] [pre-commit.ci] auto fixes from pre-commit.com hooks

---
 test_cases/stdlib/collections/check_counter.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 9b6f74b4736a..921c6bea5420 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -1,5 +1,5 @@
 from collections import Counter
-from typing_extensions import assert_type, Never
+from typing_extensions import Never, assert_type
 
 
 class Foo: ...

From ab7f64c09412c85c14f527fc596cb1e98941ec9d Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Wed, 20 Mar 2024 06:49:21 +0100
Subject: [PATCH 03/19] Replace some more ints, fix a test

---
 stdlib/collections/__init__.pyi               | 22 +++++++++----------
 .../stdlib/collections/check_counter.py       |  4 ++--
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/stdlib/collections/__init__.pyi b/stdlib/collections/__init__.pyi
index ccd0023a9190..a7c8b28caead 100644
--- a/stdlib/collections/__init__.pyi
+++ b/stdlib/collections/__init__.pyi
@@ -275,26 +275,26 @@ class Counter(dict[_T, _C]):
     def elements(self) -> Iterator[_T]: ...
     def most_common(self, n: int | None = None) -> list[tuple[_T, int]]: ...
     @classmethod
-    def fromkeys(cls, iterable: Any, v: int | None = None) -> NoReturn: ...  # type: ignore[override]
+    def fromkeys(cls, iterable: Any, v: _C | None = None) -> NoReturn: ...  # type: ignore[override]
     @overload
     def subtract(self, iterable: None = None, /) -> None: ...
     @overload
-    def subtract(self, mapping: Mapping[_T, int], /) -> None: ...
+    def subtract(self, mapping: Mapping[_T, _C], /) -> None: ...
     @overload
     def subtract(self, iterable: Iterable[_T], /) -> None: ...
     # Unlike dict.update(), use Mapping instead of SupportsKeysAndGetItem for the first overload
     # (source code does an `isinstance(other, Mapping)` check)
     #
     # The second overload is also deliberately different to dict.update()
-    # (if it were `Iterable[_T] | Iterable[tuple[_T, int]]`,
+    # (if it were `Iterable[_T] | Iterable[tuple[_T, _C]]`,
     # the tuples would be added as keys, breaking type safety)
     @overload  # type: ignore[override]
-    def update(self, m: Mapping[_T, int], /, **kwargs: int) -> None: ...
+    def update(self, m: Mapping[_T, _C], /, **kwargs: _C) -> None: ...
     @overload
-    def update(self, iterable: Iterable[_T], /, **kwargs: int) -> None: ...
+    def update(self, iterable: Iterable[_T], /, **kwargs: _C) -> None: ...
     @overload
-    def update(self, iterable: None = None, /, **kwargs: int) -> None: ...
-    def __missing__(self, key: _T) -> int: ...
+    def update(self, iterable: None = None, /, **kwargs: _C) -> None: ...
+    def __missing__(self, key: _T) -> _C: ...
     def __delitem__(self, elem: object) -> None: ...
     if sys.version_info >= (3, 10):
         def __eq__(self, other: object) -> bool: ...
@@ -307,10 +307,10 @@ class Counter(dict[_T, _C]):
     def __pos__(self) -> Counter[_T]: ...
     def __neg__(self) -> Counter[_T]: ...
     # several type: ignores because __iadd__ is supposedly incompatible with __add__, etc.
-    def __iadd__(self, other: SupportsItems[_T, int]) -> Self: ...  # type: ignore[misc]
-    def __isub__(self, other: SupportsItems[_T, int]) -> Self: ...
-    def __iand__(self, other: SupportsItems[_T, int]) -> Self: ...
-    def __ior__(self, other: SupportsItems[_T, int]) -> Self: ...  # type: ignore[override,misc]
+    def __iadd__(self, other: SupportsItems[_T, _C]) -> Self: ...  # type: ignore[misc]
+    def __isub__(self, other: SupportsItems[_T, _C]) -> Self: ...
+    def __iand__(self, other: SupportsItems[_T, _C]) -> Self: ...
+    def __ior__(self, other: SupportsItems[_T, _C]) -> Self: ...  # type: ignore[override,misc]
     if sys.version_info >= (3, 10):
         def total(self) -> int: ...
         def __le__(self, other: Counter[Any]) -> bool: ...
diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 921c6bea5420..7c929db47abb 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -1,12 +1,12 @@
 from collections import Counter
-from typing_extensions import Never, assert_type
+from typing_extensions import assert_type
 
 
 class Foo: ...
 
 
 # Test the constructor
-assert_type(Counter(), Counter[Never, int])
+# assert_type(Counter(), Counter[Never, int])  # pyright derives "Unknown" instead of "Never"
 assert_type(Counter(foo=42.2), Counter[str, float])
 assert_type(Counter({42: "bar"}), Counter[int, str])
 assert_type(Counter([1, 2, 3]), Counter[int, int])

From 44ed688d5343e4f62b40536c3489589dd6493208 Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Wed, 20 Mar 2024 06:55:23 +0100
Subject: [PATCH 04/19] Add generic arguments

---
 stdlib/collections/__init__.pyi | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/stdlib/collections/__init__.pyi b/stdlib/collections/__init__.pyi
index a7c8b28caead..e8f8e24d22f7 100644
--- a/stdlib/collections/__init__.pyi
+++ b/stdlib/collections/__init__.pyi
@@ -300,12 +300,12 @@ class Counter(dict[_T, _C]):
         def __eq__(self, other: object) -> bool: ...
         def __ne__(self, other: object) -> bool: ...
 
-    def __add__(self, other: Counter[_S]) -> Counter[_T | _S]: ...
-    def __sub__(self, other: Counter[_T]) -> Counter[_T]: ...
-    def __and__(self, other: Counter[_T]) -> Counter[_T]: ...
-    def __or__(self, other: Counter[_S]) -> Counter[_T | _S]: ...  # type: ignore[override]
-    def __pos__(self) -> Counter[_T]: ...
-    def __neg__(self) -> Counter[_T]: ...
+    def __add__(self, other: Counter[_S, _C]) -> Counter[_T | _S, _C]: ...
+    def __sub__(self, other: Counter[_T, _C]) -> Counter[_T, _C]: ...
+    def __and__(self, other: Counter[_T, _C]) -> Counter[_T, _C]: ...
+    def __or__(self, other: Counter[_S, _C]) -> Counter[_T | _S, _C]: ...  # type: ignore[override]
+    def __pos__(self) -> Counter[_T, _C]: ...
+    def __neg__(self) -> Counter[_T, _C]: ...
     # several type: ignores because __iadd__ is supposedly incompatible with __add__, etc.
     def __iadd__(self, other: SupportsItems[_T, _C]) -> Self: ...  # type: ignore[misc]
     def __isub__(self, other: SupportsItems[_T, _C]) -> Self: ...

From 923d8e20cc5e74b19966aa7e7ec1365fcb354bf1 Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Wed, 20 Mar 2024 07:02:35 +0100
Subject: [PATCH 05/19] Add more tests

---
 test_cases/stdlib/collections/check_counter.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 7c929db47abb..a277c4ee54be 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -13,12 +13,14 @@ class Foo: ...
 
 int_c: Counter[str] = Counter()
 assert_type(int_c, Counter[str, int])
+assert_type(int_c["a"], int)
 int_c["a"] = 1
 int_c["a"] += 3
 int_c["a"] += 3.5  # type: ignore
 
 float_c = Counter(foo=42.2)
 assert_type(float_c, Counter[str, float])
+assert_type(float_c["a"], float)
 float_c["a"] = 1.0
 float_c["a"] += 3.0
 float_c["a"] += 42
@@ -26,6 +28,7 @@ class Foo: ...
 
 custom_c: Counter[str, Foo] = Counter()
 assert_type(custom_c, Counter[str, Foo])
+assert_type(custom_c["a"], Foo)
 custom_c["a"] = Foo()
 custom_c["a"] += Foo()  # type: ignore
 custom_c["a"] += 42  # type: ignore

From f460e39ddf6fdc8d88ffa0d792b197bab2f655ab Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Wed, 20 Mar 2024 07:05:39 +0100
Subject: [PATCH 06/19] Disable a test

---
 test_cases/stdlib/collections/check_counter.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index a277c4ee54be..291b8acaa061 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -31,4 +31,5 @@ class Foo: ...
 assert_type(custom_c["a"], Foo)
 custom_c["a"] = Foo()
 custom_c["a"] += Foo()  # type: ignore
-custom_c["a"] += 42  # type: ignore
+# pyright incorrectly accepts the next line
+# custom_c["a"] += 42  # type: ignore

From 424d3c02ceaa63765967dfddad097fdcf7f754fa Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Wed, 20 Mar 2024 07:07:45 +0100
Subject: [PATCH 07/19] Make pyright happy

---
 test_cases/stdlib/collections/check_counter.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 291b8acaa061..4df4ee6dc640 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -32,4 +32,4 @@ class Foo: ...
 custom_c["a"] = Foo()
 custom_c["a"] += Foo()  # type: ignore
 # pyright incorrectly accepts the next line
-# custom_c["a"] += 42  # type: ignore
+# custom_c["a"] += 42  # xtype: ignore

From e3369269901d010d97cf10a9d5f391d5b3210a8c Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Wed, 20 Mar 2024 07:14:40 +0100
Subject: [PATCH 08/19] pyright is quite unhappy today ...

---
 test_cases/stdlib/collections/check_counter.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 4df4ee6dc640..7bf2813ed388 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -7,19 +7,19 @@ class Foo: ...
 
 # Test the constructor
 # assert_type(Counter(), Counter[Never, int])  # pyright derives "Unknown" instead of "Never"
-assert_type(Counter(foo=42.2), Counter[str, float])
-assert_type(Counter({42: "bar"}), Counter[int, str])
-assert_type(Counter([1, 2, 3]), Counter[int, int])
+assert_type(Counter(foo=42.2), "Counter[str, float]")
+assert_type(Counter({42: "bar"}), "Counter[int, str]")
+assert_type(Counter([1, 2, 3]), "Counter[int, int]")
 
 int_c: Counter[str] = Counter()
-assert_type(int_c, Counter[str, int])
+assert_type(int_c, "Counter[str, int]")
 assert_type(int_c["a"], int)
 int_c["a"] = 1
 int_c["a"] += 3
 int_c["a"] += 3.5  # type: ignore
 
 float_c = Counter(foo=42.2)
-assert_type(float_c, Counter[str, float])
+assert_type(float_c, "Counter[str, float]")
 assert_type(float_c["a"], float)
 float_c["a"] = 1.0
 float_c["a"] += 3.0
@@ -27,7 +27,7 @@ class Foo: ...
 float_c["a"] += "42"  # type: ignore
 
 custom_c: Counter[str, Foo] = Counter()
-assert_type(custom_c, Counter[str, Foo])
+assert_type(custom_c, "Counter[str, Foo]")
 assert_type(custom_c["a"], Foo)
 custom_c["a"] = Foo()
 custom_c["a"] += Foo()  # type: ignore

From 2f5105bfb67936c43b55892e359e483be5dfe7ed Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Wed, 20 Mar 2024 07:17:03 +0100
Subject: [PATCH 09/19] ...

---
 test_cases/stdlib/collections/check_counter.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 7bf2813ed388..a9b857ff97a5 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from collections import Counter
 from typing_extensions import assert_type
 

From dcf86cf418aeaf3a3be7dcb8cab1729c746d3b87 Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Sun, 7 Apr 2024 15:18:38 +0200
Subject: [PATCH 10/19] Improve tests

---
 test_cases/stdlib/collections/check_counter.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index a9b857ff97a5..42b5f9212814 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -8,7 +8,10 @@ class Foo: ...
 
 
 # Test the constructor
-# assert_type(Counter(), Counter[Never, int])  # pyright derives "Unknown" instead of "Never"
+# We can't test the type of the constructor directly, because mypy and pyright
+# derive different types (`Never` vs. `Unknown`) for the first type variable.
+for value in Counter().values:
+    assert_type(value, int)
 assert_type(Counter(foo=42.2), "Counter[str, float]")
 assert_type(Counter({42: "bar"}), "Counter[int, str]")
 assert_type(Counter([1, 2, 3]), "Counter[int, int]")

From caa5b1425ba9be2f72fb7d638d403c7859906ebd Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Sun, 7 Apr 2024 15:27:16 +0200
Subject: [PATCH 11/19] Fix test

---
 test_cases/stdlib/collections/check_counter.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 42b5f9212814..4fc8752270a0 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -10,7 +10,7 @@ class Foo: ...
 # Test the constructor
 # We can't test the type of the constructor directly, because mypy and pyright
 # derive different types (`Never` vs. `Unknown`) for the first type variable.
-for value in Counter().values:
+for value in Counter().values():
     assert_type(value, int)
 assert_type(Counter(foo=42.2), "Counter[str, float]")
 assert_type(Counter({42: "bar"}), "Counter[int, str]")

From e10c23c9d46cbb35514fb0bef6eede1fc5b2010b Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Sun, 7 Apr 2024 15:41:05 +0200
Subject: [PATCH 12/19] Revert changes that make pyright unhappy

---
 test_cases/stdlib/collections/check_counter.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 4fc8752270a0..a9b857ff97a5 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -8,10 +8,7 @@ class Foo: ...
 
 
 # Test the constructor
-# We can't test the type of the constructor directly, because mypy and pyright
-# derive different types (`Never` vs. `Unknown`) for the first type variable.
-for value in Counter().values():
-    assert_type(value, int)
+# assert_type(Counter(), Counter[Never, int])  # pyright derives "Unknown" instead of "Never"
 assert_type(Counter(foo=42.2), "Counter[str, float]")
 assert_type(Counter({42: "bar"}), "Counter[int, str]")
 assert_type(Counter([1, 2, 3]), "Counter[int, int]")

From b107d205002a99cb08727ad08cfdfacc98066869 Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Tue, 9 Apr 2024 11:03:45 +0200
Subject: [PATCH 13/19] Use explicit cast in test cases

---
 test_cases/stdlib/collections/check_counter.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index a9b857ff97a5..0129df47b74d 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from collections import Counter
+from typing import cast
 from typing_extensions import assert_type
 
 
@@ -28,10 +29,9 @@ class Foo: ...
 float_c["a"] += 42
 float_c["a"] += "42"  # type: ignore
 
-custom_c: Counter[str, Foo] = Counter()
+custom_c = cast("Counter[str, Foo]", Counter())
 assert_type(custom_c, "Counter[str, Foo]")
 assert_type(custom_c["a"], Foo)
 custom_c["a"] = Foo()
 custom_c["a"] += Foo()  # type: ignore
-# pyright incorrectly accepts the next line
-# custom_c["a"] += 42  # xtype: ignore
+custom_c["a"] += 42  # type: ignore

From 4723e02e5b365ca7a69024d409f76e94c7741139 Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Tue, 9 Apr 2024 11:18:05 +0200
Subject: [PATCH 14/19] Add a test

---
 test_cases/stdlib/collections/check_counter.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 0129df47b74d..9e3dcb86e038 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -10,6 +10,7 @@ class Foo: ...
 
 # Test the constructor
 # assert_type(Counter(), Counter[Never, int])  # pyright derives "Unknown" instead of "Never"
+assert_type(next(Counter().values()), int)
 assert_type(Counter(foo=42.2), "Counter[str, float]")
 assert_type(Counter({42: "bar"}), "Counter[int, str]")
 assert_type(Counter([1, 2, 3]), "Counter[int, int]")

From 39aa741481a64f2c42d043f4f62235e5a165b3d9 Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Tue, 9 Apr 2024 11:36:50 +0200
Subject: [PATCH 15/19] Try using `Any` in type assertion

---
 test_cases/stdlib/collections/check_counter.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 9e3dcb86e038..7c5b23c6b2c0 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from collections import Counter
-from typing import cast
+from typing import Any, cast
 from typing_extensions import assert_type
 
 
@@ -10,6 +10,7 @@ class Foo: ...
 
 # Test the constructor
 # assert_type(Counter(), Counter[Never, int])  # pyright derives "Unknown" instead of "Never"
+assert_type(Counter(), "Counter[Any, int]")
 assert_type(next(Counter().values()), int)
 assert_type(Counter(foo=42.2), "Counter[str, float]")
 assert_type(Counter({42: "bar"}), "Counter[int, str]")

From f9a14bab10c44137ab5a62f35eb5860299b7e24b Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Tue, 9 Apr 2024 11:38:32 +0200
Subject: [PATCH 16/19] Fix test

---
 test_cases/stdlib/collections/check_counter.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index 7c5b23c6b2c0..ed9ff93618cb 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -11,7 +11,7 @@ class Foo: ...
 # Test the constructor
 # assert_type(Counter(), Counter[Never, int])  # pyright derives "Unknown" instead of "Never"
 assert_type(Counter(), "Counter[Any, int]")
-assert_type(next(Counter().values()), int)
+assert_type(next(iter(Counter().values())), int)
 assert_type(Counter(foo=42.2), "Counter[str, float]")
 assert_type(Counter({42: "bar"}), "Counter[int, str]")
 assert_type(Counter([1, 2, 3]), "Counter[int, int]")

From 3fe47e03c904ba4d9162379d1b367ba9b8ff7e90 Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Tue, 9 Apr 2024 11:44:42 +0200
Subject: [PATCH 17/19] Streamline tests

---
 test_cases/stdlib/collections/check_counter.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/test_cases/stdlib/collections/check_counter.py b/test_cases/stdlib/collections/check_counter.py
index ed9ff93618cb..581ba67b98e4 100644
--- a/test_cases/stdlib/collections/check_counter.py
+++ b/test_cases/stdlib/collections/check_counter.py
@@ -9,9 +9,8 @@ class Foo: ...
 
 
 # Test the constructor
-# assert_type(Counter(), Counter[Never, int])  # pyright derives "Unknown" instead of "Never"
+# mypy derives Never for the first type argument while, pyright derives Unknown
 assert_type(Counter(), "Counter[Any, int]")
-assert_type(next(iter(Counter().values())), int)
 assert_type(Counter(foo=42.2), "Counter[str, float]")
 assert_type(Counter({42: "bar"}), "Counter[int, str]")
 assert_type(Counter([1, 2, 3]), "Counter[int, int]")

From a15d40713019ef18e9d32717a3ccdfebfeb11519 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Mon, 14 Apr 2025 09:16:39 +0000
Subject: [PATCH 18/19] [pre-commit.ci] auto fixes from pre-commit.com hooks

---
 stdlib/collections/__init__.pyi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/collections/__init__.pyi b/stdlib/collections/__init__.pyi
index 9eea4e53a23a..a0c7e54e89aa 100644
--- a/stdlib/collections/__init__.pyi
+++ b/stdlib/collections/__init__.pyi
@@ -2,7 +2,7 @@ import sys
 from _collections_abc import dict_items, dict_keys, dict_values
 from _typeshed import SupportsItems, SupportsKeysAndGetItem, SupportsRichComparison, SupportsRichComparisonT
 from types import GenericAlias
-from typing import Any, ClassVar, Generic, NoReturn, SupportsIndex, TypeVar, final, overload
+from typing import Any, ClassVar, NoReturn, SupportsIndex, TypeVar, final, overload
 from typing_extensions import Self
 
 if sys.version_info >= (3, 10):

From 2b1a6a07a6c1079ad9b33eab4aa4ee74313fa420 Mon Sep 17 00:00:00 2001
From: Sebastian Rittau <srittau@rittau.biz>
Date: Mon, 14 Apr 2025 11:20:46 +0200
Subject: [PATCH 19/19] Remove unnecessary class-scoped variables

---
 stdlib/collections/__init__.pyi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/stdlib/collections/__init__.pyi b/stdlib/collections/__init__.pyi
index a0c7e54e89aa..f170566ea119 100644
--- a/stdlib/collections/__init__.pyi
+++ b/stdlib/collections/__init__.pyi
@@ -273,9 +273,9 @@ class Counter(dict[_T, _C]):
     @overload
     def __init__(self, iterable: None = None, /) -> None: ...
     @overload
-    def __init__(self: Counter[str, _C], iterable: None = None, /, **kwargs: _C) -> None: ...
+    def __init__(self: Counter[str], iterable: None = None, /, **kwargs: _C) -> None: ...
     @overload
-    def __init__(self: Counter[_T, _C], mapping: SupportsKeysAndGetItem[_T, _C], /) -> None: ...
+    def __init__(self, mapping: SupportsKeysAndGetItem[_T, _C], /) -> None: ...
     @overload
     def __init__(self, iterable: Iterable[_T], /) -> None: ...
     def copy(self) -> Self: ...